A large majority of women color their hair, either to cover gray or change hair color. There are generally three types of hair color: permanent, semi-permanent, and temporary. The term "permanent" generally refers to oxidative dyes, which provide hair color that lasts about four to six weeks. Oxidative hair dyes are usually sold in the form of a two component kit. In one container is an aqueous alkaline composition in the liquid, gel, or creme form that contains oxidative dyes in addition to other ingredients. In the other container is a developer composition that contains an oxidizing agent, usually hydrogen peroxide. The two components are mixed immediately prior to use and applied to hair. The relatively high pH of the composition causes the hair shaft to swell, permitting the dye precursors in the lotion to penetrate the hair shaft. The oxidizing agent then oxidizes the dye precursors, which then combine to form large color molecules within the hair shaft. The mixture is left on the hair for an appropriate period of time, generally 20 to 60 minutes, then rinsed off with water. While consumers who use oxidative dyes appreciate that oxidative dyes provide permanent color, there are certain drawbacks to oxidative dyes that consumers find less than desirable. For example, the peroxide necessary to make the oxidative dye process operable sometimes causes sensitive hair to become dry and brittle. In addition, oxidatively colored hair may undergo further chemical change after two to three weeks, causing the color to fade or exhibit a hue different from the original color. The degree of change varies, with red shades being most susceptible.
Semi-permanent hair color differs in that the dye molecules are preformed prior to application to the hair, and the size of the molecules does not change during the dye process. Semi-permanent dyes will wash out of the hair after about six to twelve shampoos. Semi-permanent hair color is perceived to be gentler to hair because peroxide is not used, as in oxidative hair color.
Temporary hair color is color applied to the hair surface, which is removed with one shampoo. Temporary haircolor is most often used when a unique effect is desired for one day.
Accordingly, the gold standard for haircolor is to provide a composition which does not utilize oxidizing agents such as hydrogen peroxide. The haircolor should provide the same intensity and duration of color as found in oxidative dyes, yet at the same time be gentle and non-drying to the hair.
The object of the invention is to provide a novel class of compounds for use in coloring the hair.
Another object of the invention is to provide a class of polymeric compounds for use in coloring hair, which can be used in hair color systems which are free of oxidizing agents, or contain them in substantially reduced amounts.
Another object of the invention is to provide a method for coloring hair with a haircolor composition containing these polymeric compounds.